Heating apparatus



Dv L. SUMMEY HEATING APPARATUS Sept. 30, 1930.

Filed May 3l 1923 Sept. 30, 1930, DA L SUMMEY 1,776,823

HEATING APPARATUS Filed Kay 5l, 1923 7 SheQTs-Shee 2 gvwentoz Sept. 30,1930. D, SUMMEY lI'I'ING' APPARATUS Filed lay 5l, 1923 7 Sheets-Sheetgpt. 30, 1930. o. L. sUMMl-:Y 1,776,823

' HEATING APPARATUS Sept 30, 1930- D. l. suMMEY HEATING APPARATUS Filedlay 3l, 1923 vwanboz 7 Sheets-Sheet Sept. .30, 1930.l D. l... sUMMEY1,7761823 HEATING APPARATUS Filed Kay 51, 1923 7 Sheets-Sheet 6 n'oenboz@51j da @Hom 4 m@ @i5/e@ Sept 30, 1930. D L SUMMEY 1,776,823

HEATING APPARATUS Filed May A51, 1923 7` Sheets-Sheet 7 mnuuumm ffy/f.'

Patented Sept. 30, 1930 PATENT OFFICE DAVID Sm, 6l' WATERBUBY,CONNECTICUT HEATING APPARATUS Application med Kay $1, 1988. Serial No.642,411.

This invention relates to heating appara- `nections and arrangements ofthe hair pin tus and more particularly to annealing furnaces.

It is one of the principal objects of the in vention to provide aneicient electric heating furnace that is economical as to theconsumption of electric current for heating' the furnace and thematerial placed therein.

It is a further object of theinvention to provide a heating apparatuscapable of a l,large output, that requires a mlnimum of manual labor.

It is still a further object of the invention to provide an eicientheating apparatus utilizing electric resistance heating elements inwhich the heating elements may be removed and replaced without anymaterial tearing down of the furnace.

With these general objects'in view, the invention consists in the.features, combinations, details of construction and arrangement ofparts which will first be described in connection with the accom anyingdrawings and then more particularly pointed out.

In the drawingsl 1 Fig. 1 is a view, partly in longitudinal section andpartly diagrammatic of a heating apparatus constructed in accordancewith the invention; 1

Fig. 2 is a vertical transverse sectional view through the heatingchamber; l Fig. 3 is an enlarged cross-sectional view taken on the line3-3 of Fig. 2; f Fig. 4 is a plan view of a resistance wire removed,with part broken away;

Fig.. 5 is a similar view of a modied form of resistance wire; v

Fig. 6 is a detail view showing part of a conveyor chain in plan;` f

Fig. 7 is a'detail view Showing part of a conveyorv and its pulley inside elevation; Fig. 8 is a longitudinal vertical sectional view of theheating chamber; l Fig. 9 is a view of the same in side elevation; y n iFig. 10 is a schematic view showing the-alternate arrangements of thewire connections; l i j Fig. 11 i a plan view of a hair pin form ofwire;

' tion portion ofthe wire. It Will be under- Fig. 12 is a schematic viewshowing' the con# wires;

Fig. 13 is a view, partly in vertical transverse section and partlydiagrammatic of a modified form of apparatus in which the coils areheated inductively;

Fi 14 isa view of the samepartly in longitu inal vertical section;

Figs. 15 and 16 are views in vertical section and plan of a coil ofmaterial and a binder;

Fig. 17 is a diagrammatic'view showing a pyrometer control; and

Fig. 18 is a wiring diagram for the same.

Referring to the drawings, the apparatus illustrated as an example inFigs. 1-10 cornprising along furnace chamber'lO enclosed by a housing 11of brick and fire brick or other suitable material.

There is provided heat supplying means,l such, for example, as -electricresistance elements, and in structures embodying the invention to thebest advantage these elements are arranged to supply heating zones ofvarying degree. Although capable. of various constructions, in theembodiment illustrated, supported and distributed as hereinafter descried, are a plurality of long, straight nickel-chromium wires 12 runninglengthwise of the furnace and extending almost the entire length of theenclosed chamber 10. In order to provide zones of varying degrees'ofheat', for a purpose later referred to, the individualwires 12 have avarying cross-section. Y In the particular embodiment illustrated eachwire is formed with, a small or high resistance 'cross-section at itscentral portion and a large or low resistance crosssection at its ends.With this construction the heating effect of the wires'at the ends ofthe chamber. is substantially immaterial and at the central part of thechamber it is relatively high, the length of the hot zone beingdetermined by the' length of the small cross-sec-4 stoodthat the extentof the various cross-- sections may be varied as desired and that whilethe wires shown are all alike as to crosssectional arrangement, thevarious wires may differ in this respect. Further, by stepping l.

` 55 ltrates the circuit scheme for the wires and down thecross-section, the heating eti-'ect can f be gradually increased anddecreased. Such various constructions, in the embodiment il-l lustrated,set at spaced intervals along vthe chamber 10, are a pluralityoftransverse supkportiiig frames 14, which are seated in the chamberwalls. These frames are of skeleton construction and carried thereby areperfo- 'rate blocks 16 of insulating material, sucli as tile. Theperforations of the similarly' located blocks of the several frames arelined up lengthwise of the chamber so that the resistance wires 12 maybe threaded through them ina straight line. The frames themselves aremade of a material capable of withstanding -continued high .temperatureswithout structural deformation and without oxidizing. For this purpose,nickel-chromium andv similar alloys have been found suitable. That is,the frames may be made of a metal having substantially the Isame heatresisting characteristics as the metal of the wires. p

The wires 12 terminate just beyond the final frame at each end of thechamber andthe ends are connected in circuit. To neutralize the fieldscreated by the current in wires 12, thus avoiding inductive eiects, inthe embodiment shown, alternate wires are connected at one end, to onebus bar and the other wires are connected to a second bus bar, thedirection side the latter.

of flow being lreversed in the two sets.A As shown in Figs. 2 and 3 theends of one set of wires are connected by detachable clamps 17 with busbars 18 carried by the housing walls and running around the four sidesthereof. The ends of the alternate wires are connected by detachableclamps 17 with bus bars 181 similar to bus bars 18 and yarrangedalongdiagrammatically onlypin Fig. 2, the full constructions being shownin Fig. 3. The bus 'bars 18 and 181are connected to main leads 13, 15Vand 131, 151, in such manner that the v plus ends of the wires of oneset are at the same end of thel furnace as the minus ends of the wiresof the other set.' Fig. 10 illusbus bars.

While round wires and round holes in the insulators have been shown, itis to be understood that other cross-sectional shapes may be used such,for example, as ribbon or triangular s apes.

There is provided conveyor means for moving the material to be heatedthrough the furnace chamber, In structures embodying The clamps 17 areshown1 the invention to the best advantage the conveyor ,means comprisesan endless chain, and where the type o material permits, the conveyor isarranged to carry material on bothA strands. While capable of variousconstructions, in that hereyshown'as an example, which isypartcularly""adapted for heating large coils of metal, such, forexample, as brass,

Vthe chain is made up of flat, skeleton links 25 which are functionallyreversible. That is,

coils may be carried on either face of the chain. Each link has, at oneside, two double lugs 26 and at the other side, two single lugs 27. Thelinks being assembled, they are con- 'links and pins in the presentembodiment, are

made of nickel chromium alloy. The pulleys and shafts being in therelatively cool zones may be made of ordinary steel.

While one conveyor chain only may be used, in the embodiment illustratedfour chains are provided, arranged in nested relation. That is, thereare two bottom chains side by side, and two top chains above them. Theseveral conveyor elements are duplications in the present constructions.With' lfour conveyor elements in nested relation, a large conveyorcapacity is obtained with a relatively small housing and there -ismarked economy in heating, as the loss of heat by radiation per unitconveyor is relatively small.

In order to provide eiective` and economical heating, provision is 'madewhereby each strand of each conveyor is surroundedy by resistanceelements. To this end, as here shown as an example, the'supportingframes 14: have central legs 19 and three cross bars 20, skeleton inform and carrying perforate insulating blocks 16. Through these blocksare threaded additional resistance wires 12 like those alreadydescribed. As appears in Fig. 2, the wires supported by the cross barsof the frames are alternately connected by clamps 17 with crossbus barextensions 21 and 211, connected respectively with the bus bars 18 and181. The wires supported by the vertical legs of the frames aresimilarly connected with vertical bus bar extensions 22 and 221 alsoconnected to bus bars 18 and 181.

With the construction described, the connections to the bus bars, thebus bars themselves and the take out leads to the supply circuit arealll located in the relatively cool zones of the furnace and loss ofheat through While the Wires are shown as all connected in a singlesupply circuit, it will be understood that they may be grouped for anumber vof transformers, which also makes pos- 5 sible a heat control byvoltage regulation.

The cross bars 20 of the frames 14 also serve as support for rails orangle pieces 29 which serve as tracks Kon which the conveyor chains runand which are suitably vmade of the same metal as the chains, e. g.Ynickelchromium alloy. u

If desired, the frames 14 may be grouped -in tvvo sets, alternate framesserving only to support the'rails 29, the other frames serv- 15 ing onlyto carry the insulating blocks 16.

That is, in the construction referred to, the frames which support thechains do not support the Wires and the Wire supporting frames do notsupport .the rails, and chains.

l20 With such a construction, vibration of the insulating blocks isavoided and there is little or no danger of current leakages.

With the construction above described, coils of material to be heated,indicated at 34, being loaded and unloaded as later described, arecarried in one direction on the top strandl of each chain and in theopposite direction on the bottom strand `of each chain. Thus there areeight rows of conveyed material moving through the furnace chamber, fourin one direction and four in the opposite direction. As appears moreclearly in'- F ig.- 2, each row of moving material, i. e., each strandof each chain, is surrounded bv resistance heating Wires. Consideringany one conveyor as an example, asthe coils on the top strand leave thecentral hot zone of Lthe furnace chamber, they meet the oppositelymoving cold coils on the bottom strand in the relatively cool end zone,The heat given off from the hot coils gives the cold coils a preheatingand thus an economy in heat supply is effected. The same preheatingtakes place at the other end of the furnace chamber, the incoming coldcoils on the top strand being preheated by the outgoing hot coils on thebottom strand.

Electricity as a heating medium gives the advantage, among others, of anaccurate and uniform heating effect and, due to the constructiondescribed, high furnace efficiency is made possiblel and the furnace isconsequently economical as to the heating medium, even With electricity.Both strands ofthe conveyor'chains move through the heating zone and thetemperature of the chains al- Ways remains much higher than atmosphere.

z With a double duty chain the dead load is reduced to a minimum, heatis economized and the investment cost of material is substantiallyreduced.

Should any resistance element break dovvn,`

its removal and replacement can be accomplished without taking down thefurnace or 65 substantial portions thereof. A .Workman can enter therelatively cool end of the furnace through doors hereinafter described,detach the clamp 17 of the Wire in question and draw out the Wire. rl`heWire may be removed from the chamber through a normally closed hole inthe end wall of the housing, for example, a hole provided by the removal'of one ormore of the bricks that make up the Wall" In thesame manner anew or rclpaired Wire can be threaded through the supports and connectedup in circuit. In

this connection it is noted that the Walls of the furnace form merely ahousing, the heating elements being supported independently of thehousing Walls. A further advantage of the constructiondescribed is thatit makes possible the use of standard sizes of insulating blocks insteadof, numerous special sizes.

There is provided means for removing the material to be heated, such ascoils, from the conveyor and meansfor feeding material to as thelatteris advanced by the conveyor.

The rod 44 isconnected to a piston 45 Working in a cylinder 46. Openinginto opposite ends of the `cylinder 46 are pipes 47, 48,

connected by a 4-Way valve 49 vwith an exhaust pipe 50 and a supply pipe51. Pipe 51 H leads to any suitable source of fluid pressure, such ascompressed air, not shovvn.

When the hooked rod .44 receives a coil (as appears in Fig. 1) the valve49 is operated, by means hereinafter described, to admit air throughpipe 47, thus causing piston 45 to Withdraw the rod 44, the cylinderexhausting through pipe 48, valve 49and pipe 50. By this operation, thecoil is drawn out of the furnace chamber across platform 42 onto theconveyor 43, which carries it away. When valve 49 is reversed, as laterdescribed. the piston has a reverse movement and the rod 44 is replacedin position in the chamber to receive the next coil.

The'discharge conveyor 43 is shown diagrammatically as a short Aendlessbelt or chain. It will be understood that it may be extended to carrythe discharged coil to any point desired. nstead of a dischargeconveyor, there may be used Van elevator or the like to carry theremoved coil to a quenc ing it. p At' the opposite end of the furnace isan opening 53 having a platform 54 like platform 42. Coils are broughtup to the platform 54 by a 'conveyor 55 like conveyor 43. The coils arepushed across platform 54 onto the conveyor chain by a push rod 56 havin5 a curved end to embrace a coil. The pus ,-rod y56 is connected withthe piston'of aluid pressure unit 57 that is like the unit justdescribed. By the operation of the valve of this unit 57, the rod 56 iscaused to push a coil onto the conveyor chain in the furnace and iswithdrawn for the next loading operi ation.

Doors are provided for openings 40 and 53 and there is provided meansfor operating these doors. Although capable of various constructions, inthe present embodiment, the opening 40 is normally closed by a slidingdoor 41, notched or slotted to accommodate the platform 42 and the rod44. This door is operated by a lever 59 connected by a link 60 with thepiston rod 61 of a fluid pressure unit 62, like the units abovedescribed. lBy operation of the valve of iuid pressure unit 62, the door41 is lcaused to o en and close.

5 A similar door 63 closes opening 53 and is operated by lever 64 andfluid 'pressure unit 65 that are duplicates of the similar elementsassociated with door 41. f I

.There is provided means for operating the y several valves of the fluidpressure uni-ts above referred to and in constructions embodying theinvention to the best advantagel this operation is automatic and iscontrolled by the movement of either the conveyor chain 3 or the coilscarried thereby. Although capable of various constructions, in thathere' shown as an example, in line with the conveyor chain at thedischarge end, is a contact plunger 68 slidable in the end wall of thefurnace and normally held by a spring 69 in a position to be engaged bya coil as the latter moves into the embrace of the hooked rod 44. Theother end of plunger 68 carries the contact member of a relay 70. This acoil of material is moved into contact with plunger 68, relay 70 isclosed'and through Y the connections describedthe fluid pressure' unitsare operated toopen the door and'withdraw the discharge rod, thusremoving the coil as above described.- Y

In the presentembodiment the feeding 0peration is controlled by thechain movement, so that the coils will be fedin properly spaced relaylocated in a shunt across a main line .nected by lever 76 with the valveof Huid pressure `unit 62 that operates door 41. When relation totheconveyor chain. To this end, as here shown as an example, on the shaft32, which drives the chain pulley, is a ratchet wheel 80 having aluralit of notches'81. Riding on the perip ery o the Wheel 80 is apivotally mounted detent 82, which drops into the notches 81 as thewheel rotates. The notches are so spaced that one is presented to thedetent each time it is desired to feed a coil. The detent carries an arm83 on which is mounted the contact-member of a relay 84 located in ashunt across the main line wire 71, and in which is connected oneWinding of a reversely Wound solenoid 85. The core of this solenoid isconnected by lever 86 with the valve of fluid pressure unit 57. Inparallel With the shunt just described is a loop including one Windingof a reversely wound solenoid 87 the core of which is connected by lever88 with the valve of fluid pressure unit 65. When the detent 82 dropsinto a notch 81, the relay 84 is closed. Solenoids 85, 87 being thusactuatedoperate the valves of fluid pressure units 57, 65, to cause door63 to be opened and pusher 56 to push a coil onto the conveyor chain.

Provision is made for automatically causing the return movements of therods 44, 56 vand the doors 41, 63.y To this end, as here shown as anexample, carried by the hooked rod 44 is a trip arm 90 positioned to tria spring pressed lever 91 as the rod 44 reac es the end of the dischargestroke. This lever 91 is connected with the contact member of a relay 92located in a shunt across-the main line wire 71, and in which isconnected the second or reverse Winding of solenoid 73. v

In parallel with this shunt is a loop including the second or reverseWinding of solenold 75. When trip arm 90 causes the closing of relay 92the cores of the two' solenoids are reversed, thus reversing the valvesof the two fluid pressure units and the rod 44 is returned to normalposition and the door 41 is closed.

The piston of fluid pressure unit 52 has a back extension 93 carrying atrip arm 94 located to trip a spring pressed lever 95 as the pusher rod56 reaches the end of its feeding stroke. This lever 95 is connectedWith the contact member of a relay 96 in a shunt across the main linewire 71, and in which is connected the second or reverse winding ofsolenoid 85. In parallel with this shuntis a loop including the secondor reverse Winding of solenoid 87 When the relay 96 is closed, the coresof solenoids 85, 87 are reversed, thus reversing the valves of fluidpressure units 57, 65 and the rod 56 is withdrawn and door 63 is closed.

In the above description of the loading, unloading and control features,reference has been made to the top strand of the right hand,

top conveyor chain of Fig. 2. For the lower `strand of this chain, theloading and unloadythe coils are lbrought 'up b ing ends are reversed.yBelow. the discharge opening 40 for thetocpmstrand, lin the presentvembodiment, is a fee g opening 97 for the bottom strand, this beina-continuation of opening 40.' Loading o coils is carried on bymeans ofapparatus that is a' duplication of the loadinnr means described, exceptthat a' conveyor 255 that is located at right ang es to the furnaceinstead of alongside, as in the case of conveyor 55. Figs. 8 and 9indicate a push-rod slidable in a thimble 108 located in the side 256that is a counterpart ofpush rod 56.

At the other end of the furnace, below feeding opening 53 is a dischargeopening 98 for the bottom strand, this bein shown as a continuation ofopening'53. nloading of coils is carried on by means of apparatus thatis a duplication of the unloading means described except that the coilsare carried oil by a conveyor 243'that is atright angles to the furnaceinstead ofalongside as in the case of conveyor 43. Figs. 8 and9'indicate a hooked rod 244 that is a counterpart of hooked rod 44 excet that-,it faces the opposite way in view of t e reverse direction ofthe conveyed coils.

For the lower conveyor chains, the above described pairs of loading andunloading units are duplicated.

Figs. 8 and 9 indicate the push rod 356 and the discharge rod 344 of thetop strand and the push rod 456 and discharge rod 444 of the bottomstrand. These iigures alsoshow the conveyors 355, 343 and 443 and 455for the top and bottom strands, of this lower chain. It will be 'seenthat there are on one side of the furnace four loading and fourunloading units. These units are duplicated on the other side of thefurnace forl the other two conveyor chains and no further referencethereto is necessa o In Figs. 13 an 14 there is illustrated a`modification in which the coils of material are heated inductively.l Inthe exempliiication shown, there is provided along housing 101 similarto the housing already described lexcept that it is of one-conveyorsize. Moving in the chamber ,102 formed by this housing is a conveyor-cha-in 103 for carrying coils, this chain being like the/conveyorchains already described, and running on suitably supported rails orangle pieces 104. It is i Ldriven by a shaft 105 which .rotates thepulley 106. Coils of material lare loaded onto thel top strand andunloaded from the bottom strand at the end of the chamber 102 shown atthe left in Fig. 14 by apparatus and in the coil 100 wound around thecentral leg of the core, the primary coil being connected with an.suitable source, not shown.

here is provided means for causing relaltive movement between a coil ofmaterial and ment the transformer velements (except a .part of the corelater referred to) are stationar and the coil of material is moved. Tothis end, as here ,shown as an example,

wall of housing 101, opposite the heating chamber 107, is a ram orpusher 109. Thisl pusher is connected 'to the piston of a fluid pressureunit 110 like the fluid pressure units` described,the valve beingoperated as hereinafter described.

` The pusher 109 is .positioned to transfer4 i il the heating chamber107. This table is mounted on a rod or plunger 112 connected to theypiston of a fluid pressure unit 113 like unit 110, the valve beingoperated as hereinafter described. At the time of transfer of the coilfrom the conveyor chain, the table 111 is in theldotted line positionindicated at 111 in Fig. 13. After receiving a coil the table iselevated to a osition 'ust beyond the full line position'of ig. 13. nthis position,

the table'111 makes contact with the legs 9,9

of the core and becomes the fourth leg of the core, and the coil ofmaterial is between the rima coil and thelegs of the core.

uitab e current being supplled tothe primary 100, the coil of materialacts as a secondary and the metal is heated by the induced currents setup therein. The primary coil and the core may be protected by suitableinsulation from the heat generated in the coil of material and may beair cooled if desired.

After the coil is heated, the table 111 is lowered by means of its fluidpressure unit to the dotted line osition'111" of Fig. 13, in whichposition t e coil is in line with the bottom strand of the conveyorchainif- From the table, the coil of material is transferred onto theconveyor by a pusher or ram .114

like the pusher 109. This pusher 114 is connected to the iston of afluid pressure unit 115 like the unit 110, the valve being operated ashereinafter described. .Pusher 114 is then withdrawn, and pusher 109having been withdrawn meanwhile, the table 111y is returned to position111 ready to receive the next coil of material.

lcs.

Whilethe valves of the fluid ressure units I vision is made for anautomatic control. 'In

the exemplication here shown, the valve of unit 110 is connected by alever 117 with the.

core of a reversely wound solenoid 118. One' winding ofthis solenoid isconnected in a shunt, which includes a relay 119, across a main line171, connected with a suitable source not shown. The contact member ofrelay 119 is carried on the end of a spring pressed plunger 120, similarto plunger 68, and slidable inthe end wall of t e housing 101. When acoil of material reaches properposition to be transferred to table 111,it actuates the plunger 120 and closes'rela 119.- Thus solenoid 118operates the valvel o iiid pressure unit 110 to cause pusher 109 to'move the coil onto table 111.

To lreverse the valve in order to cause return of pusher 109, the pistonof unit 110 has, as here shown, a rearextension 121 carr ing a trip arm122 positioned to trip, as t, e piston reaches the end of its transferor pushing stroke, a spring pressed lever 123. This lever is connectedwith a contact member of a rela 124 located in a shunt across the mainline 1 1 and in which is connected the second winding of solenoid 118.When relay 124 is closed the valve of fluid pressure unit 110 isreversed and pusher 109 is withdrawn. At this period in the cycle ofoperations, luid pressure'unit 113 is tending to elevate table 111, butthe parts are held against such movement 'until the table receives acoil of material.v To this end, as here shown as an example, an arm 128.on a rear extension 129 carried by the piston of unit 113 is arranged tobe engaged by a sliding stop 127, to hold the table in position 11la. Torelease this stop, on the extension 121 of unit 110, is a trip arm 151positioned and arranged to trip momentarily a spring-pressed lever 152,after the piston of unit 110 has withdrawn the pusher 109 from the pathof the table and nearly reached the end of its back stroke. This levercarries the contact `element of a relay 153 located in shunt across themain line 171 andin which is connected one winding of a reversely woundsolenoid y125. The core of this solenoid is connected by a lever 126with sliding stop 127. When relay 153 is closed, therefore, the stop 127is withdrawn and unit 113 is free to complete the elevation of table 111to coil heating position. It will Provision is made for lowering thetable l vbe apparent that, following this operation of solenoid 125 andstop 127 by the momentary closing of relay 153', the solenoid and storetain their position by the inertia of the parts until again moved aslater described.

a given time interval. To thls end, as here shown as, an example,mounted on shaft 105 is a wheel 130 having a plurality of spaced notches131. Riding on the periphery of wheel130 is a spring-pressed pivoteddetent 132, which vcarries the contact member of a relay 134. This relayis located in a shunt across` the/main line 171, in which shunt isconnected one winding of a reversely wound solenoid 135, the core ofwhich is connected by umass' a lever 136 with the valve ofiluid'pressure unit 113. When the detent 132 drops into a notch 131,relay 134 is closed and through solenoid 135 the valve of unit 113 isoperated to cause the table 111 to be lowered to position 111". Theheated coil is now positioned to be transferred back to the conveyorchain but onto the'other strand. To effect operation of pusher 114, ashere shown, on the extension 129 of table unit 113is a trip arm 137located and arranged to tripl momentarily a spring pressed lever 138 ast e piston of unit 113 reaches or nearly reaches the end of itswithdrawal stroke. This lever carries the contact element of a relay 139that is located in a shunt across the main line 171, in which shunt isconnected one winding of a reversely wound solenoid 140. vThe core ofthis solenoid is connected by a lever 141 with the valve of'iiuidpressurey unit 115. When relay 139 is closed, the valve of unit 115 isoperated to cause pusher 114 to transfer the heated coil from the table111 to the bottom strand of the conveyor chain. As in the case of themomenta trip above described, the parts are held 1n moved position,following the momentary energizing of solenoidY 140,'by inertia. l

` To reverse the valve of unit 115, thereby to cause return of pusherI114, as here shown as an example, the piston of unit 115 carries area-r extension 142 on which is a trip arm 143 arranged to trip a springpressed lever 144 as the piston completes its pushingstroke. This lever144 carries the contact element of a relay 146 that is located in ashunt across the main line 171, and in which is connected the reversewinding of solenoid 140. When relay 146 is closed the valve of unit 115is reversed and pusher 114 is withdrawn.

-To reverse the valveof unit 113, thereby to l cause the table to beelevated, following withdrawal of pusher 114, extension 142, as hereshown as an example, carries a second trip arm 145 arranged'to trip, asthe pusher 114 reaches withdrawn position, a spring pressed lever 147.This lever carries the contact ele'- ment of a relay 148 that is locatedin a shunt across the main line 171 and in which is connected thereverse winding of solenoid 135.

P Whenrelay 148 is closed, therefore, the 'valve of unit 113 isreversedand the table 111 is raised. v

Meanwhile stop 127 has been returned to stopping position in order tohold the table in line with the top strand of the 4conveyor so as toreceive a new coilof material. To

raised only, as far as position 11,1 until' the strip is a ainreleased...

s in t e case of the resistance type of furnace, a preheating andrecuperative eect is obtained with this induction type of furnace. Thatis, the yincoming cold coils on the convyor chains are preheated by theheat given o by the outgoing hot coils and the inducample, the fluidpressure units may have four l one-way-valves operated by a singly woundy 'solen0ids,.

Referring again to the resistance type of furnace, in lace of the singlestrai ht wires above descri d, wires of hair pin orm may be used. Suchav wire is shown in Fig. 11. In the exempliication illustrated, the loopof the .wire is of small or high resistance cross sectionf,t'he' endsbeing of large or loweresistancecross section. These wires are suportedas the vsingle wires are, the two ranches taking the place of tvv-.osingle wires in being threaded through or removed from the perforateinsulating blocks. In order to economize in wire material, the loops maybe alternately reversed so that the complete hair pin wire vdoes notextend the whole length of the furnace chamber. Such an ar'- lrangementis shown schematically in Fig. 12,

which also illustrates the manner of connect- Iing the wires in circuit.As shown in Fig.

' set up by the current 'in the several wires are r the present handlingapparatus.

neutralized and loss by induction isy reduced to a mmimum.

In handling coils of metal such as-those above described, at least inthe case of metal.

of the lighter gauges, it has been found advisable to firmly bind thecoils to prevent them from uncoiling. While the conveyor chains may haveribs or thelike in which the coils seat, such ya construction isconsidered impracticable with the type of loading and unloadingapparatus above described. There is provided a binder suitable for usewith ample, the coils may be boundby plain, broad bands of a metal likethe conveyor metal, in this instance, nickel chromium alloy. In Figs. 15and 16 is illustrated a skeleton frame 158 having an annular channel 159for receiving one end of the coil. This-frame may be made ofnickel-chromium alloy or the like.

' With either -type of binder, each coil is firmly bound during its entieWprocess through the apparatus described.` ith a metal such as nickelchromium alloy there is nodanger of the binders breaking down undercontinued high temperature and consequently the binders arereliable,and,1asting. 1 i

While nickel chromium alloy has been recited in the specification andclaims in con.- nection with various metal parts, it is to be understoodthat other metals having similar heat resisting characteristics ma beused as equivalents without departing` om the invention. e

There is provided means for controlling the heating temperature of theresistance type of furnace above described. This may be accomplished,for example, by providing' a constant vheat input and varying theconveyor speed in accordance with temperature changes. Although capable'of various constructions, in that here illustrated, inserted in the topwall of the furnace housing is a p rometer 501, its inner end beinglocated a jacent the path of the material on the conveyor. The pyrometeris connected by wires 502, l503 with a pyrometer dial 504 of anysuitable construction, 'comprising a pointer that.

`When the temperature at the pyrometerA falls to the lower limit,current through wires 505, 506 opens relay 507 and through theconsequent operation of contactor 509 the field resistance 510 is movedin such manner that the motor field is changed to slow down the motorand the conveyor. Assuming a constant input of heat at the furnaceresistance wires, when the speed of the conveyor is de-` creased thematerial to be heated carries away less heat and the furnace temperaturerises.

lWhen, onthe other hand, the `temperature at the pyrometer reaches theupper limit, current through wires 506, v513 operates relay 507 andcontactor 509 in the reverse direction,

whereby the eld resistance is movedtochange the motor field in a mannerto speed up the motor. The consequent increased conveyor speed resultsin more heat being carried away by the material to be heated and thetemperature in the furnace falls.

With a constant heat input and automatic control of the conveyor speedthe temperature of the material 'to be heated is automaticallycontrolled within close limits.

There is provided in the motor field circuit a field4 rheostat 516 whichcan be set by hand to give the approximate motor speed' desired for thevolume of material .to be heated. Cur- 8 l a www rent is passed throughthe resistance heating wires 12 at such -a rate as to bring the furnacebeen described it will beapparent that it may be duplicated for otherconveyors.

The operation of the several forms of apparatus will be clear from theabove without further description.

Certain featuresV above described I are claimed in a divisionalapplication Ser. No. 178,645, Patent No. 1,748,465.

What I claim is 1. In a heating apparatus, and in combination, a furnacechamber, conveyor means including an endless conveyor forsimultaneously-moving material through said chamber in oppositedirections, and electric resistance elements surrounding the severalpaths of the material moved by said conve or means.

'2. In a heating apparatus, an in combination, a furnace chamber, aplurality of conveyor means including an endless conveyor for movin alplurality of rows of material through sa1d chamber, and electricresistance elements surrounding the paths of the material moved by saidconveyor'm'eans.

3. In a heating apparatus, and in combination, a furnace chamber, anendless conveyor for moving material through said chamber, electricresistance elements above said cona veyor and electric resistanceelements between the oppositely moving strands of the conveyor. a f

4. In a heating apparatus, andin combination, a furnace chamber, anendl/ess conveyor for moving material through said chamber,

and electric resistance elements arranged above and below said conveyorand between the strands thereof.

5.' In a heating apparatus, and in combination, a furnace chamber, aplurality of endl'ess conve ors for moving material through said chamer, and a. `plurality of electric resistance elements so arranged thateach strand of each conveyor is surrounded by resistancey vfor movingmaterial through the chamber and arranged with two units above the othertwo units, and electric resistance elements around the four walls of thechamber, between each pair of conveyor units vertically and between eachpair of units horizontally, whereby each conveyor unit is surrounded byelec-- tric resistance elements.

8. In a heating apparatus, and in combina' tion, a furnace chamber, fourendless conveyors in nested relation for moving material through thefurnace, and electric resistance elements surrounding each strand ofeach conveyor.

a 9. yIn a heating apparatus, and in combination, a furnace chamber,perforate supportin means within the chamber 'and a plurallty ofelectric resistance elements comprising long straight wires, eachresistance element being removably threaded through thel perforations ofsaid supporting means.

10. In a heating a paratus, and in combination, a furnace c amber, aplurality of spaced supporting frames in said chamber insulating blockscarried by said frames, an having perforations in alinement lengthwiseof the chamber, and electric resistance ele,-l ments ,comprising lonstraight Wires threaded through said per orations.

11. In a heating apparatus, and in combination, a furnace chamber,supporting means in the chamber, a plurality of electric resistanceelements v comprising long, straight wires, threaded ,through holes insaid sup-` porting means and individually removable therefrom, abus barcarried by the chamber said resistance elements and said bus bar.

12. In a heating apparatus, a furnace chamber, electric resistance wiresin said chamber for supplying heat thereto, a con- .veyor chain formoving material through the furnace chamber and a plurality of frames inthe chamber for supporting said wires and said chains, the frames andconveyor chain being made of an alloy having substantially the same heatresisting characteristics as the resistance wires.

13. In a heating apparatus, a. furnace chamber, electric4 resistancewires in the furnace chamber having a high resistance cross section atthe c'entralpart of the chamber and low resistance cross section at thevend thereof, thereby to provide a central heating lwalls, anddetachable connections between zone, bus bars, connections between thebus bars and the resistance wires and bus bar leads, said bus bars,connections and leads being located in the relatively cool end portionsof the furnace chamber.

14. In a heating apparatus, and in combination, a furnace chamber, heatsuppl ing means, and an endless conveyor chain -having reversiblyfunctioningl links, Awhereby both strands of said chain are availablefor receiving-material to bemoved through the chamber.

15. In a heating apparatus, and in combination, a furnace chamber, anendless conveyor in the chamber, openings in the chamber walls forfeeding articles to one strand of the conveyor at one end of the chamberand to the other strand of the conveyor at the .other end of the chamberand for discharging articles from the lirst named strand at the secondnamed end of the chamber and from the second named strand at'the firstnamed end of the chamber, doors for normally closing said openings, andelectric resistance elements arranged to supply heatr in zones ofvarying degree.

16. In a heating apparatus, and in combination, a furnace chamber,conveyor means therein, heat supplying means associated with thechamber, means for feeding material to said conveyor, automaticallycontrolled by the movement of the conveyor, and means for dischargingmaterial from the conveyor, automatically controlled by the movement ofthe conveyed material.

17. In a heating apparatus, and in combination, a furnace chamber,conveyor means therein, heat supplying means 'associated with thechamber, openings in the chamber Walls l for feeding material to anddischarging it from the conveyor, feeding means, discharging means,doors for said openings, door operatinof means, and an automatic controlfor said tfeeding, discharging and operating means.

18. In a heating apparatus, and in combination, a furnace chamber,conveyor means therein, heat supplying means associated vv'ith thechamber, openings in the chamber Walls for feeding material to anddischarging it from the conveyor, feeding means including a fluidpressure unit, discharging means including a fluid pressure unit, doorsfor said openings, door operating means including a fluid pressure unit,solenoids for operating the valve mechanisms of said fluid pressureunits and automatically operated relays for controlling said solenoids.

19. In a heating apparatus, and in combination, a furnace chamber,conveyor means' therein, heat supplying means associated with thechamber, openings in the chamber Walls for feeding material to anddischarging it from the conveyor, a supply conveyor, means for bringingmaterial up to the feeding open ing, a delivery conveyor, means forcarrying material away from the discharge opening, doors for said oenings, door operating means, means for ceding material from the supplyconveyor to the' furnace conveyor,

means for dischargin material from the furnace conveyor to sai deliveryconveyor and automatic controls for said door-operating means, feedingmeans and discharging means.

20. In a heating apparatus,y a 4furnace chamber, heat supplyin means,aconveyor for moving material t rou h the furnacel chamber, an electricmotor or driving said conveyor, a variableresistance for controlling thefield of said motor and heat controlled means for varying saidresistance.

21. In a heating apparatus, a furnace chamber, electric resistance`elements for slipplying heat thereto, a conveyor for moving materialthrough the furnace chamber, an

electric motor for driving said conveyor, a pyrometer located adjacentthe path of the material in the furnace chamber, a pyromemy hand.

. DAVID L. SUMMEY.

